When did your child / younger brother or sister learn their abc's?

Every child is going to learn at different times - some earlier or later than others. My daughter knew her entire alphabet by 16 months. On that note, she also knew her Japanese "alphabet" shortly after that. She is now 5 - and a few months ago she had a friend her age (at 4) who only knew a couple letters of the alphabet - but I think since she's started preschool, she's learned them all rather quickly.